Method of forming counterbored receptacles



Sept- 11, l945 D. H. cRAvNER, JR., ErAL 21,384,444

METHOD OF FORMING COUNTERBORED RE'CEPTACLESv Filed Jun 19, 1942 Patented Sept. 11, 1945 METHOD oF FORMTNG COUNTERBORED RECEPTACLES Donald H. Cravener, Jr., Chicago, -Roy C. Ingersoll, Winnetka, and Frans B. Wendel, Chicago, Ill., assignors to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application June 19, 1942,' Serial No. 447.624

4 Claims.

This invention relates to al method of forming al counterbored receptacle. By way of exampie this invention will be described with reference to a. method of forming a trunnion bearing for a universal joint;

Certain mechanical devices 'such as trunnion bearings are required to have a cylindrical shape with one end of the cylinder closed off and with a counterbored portion near the closed end. The counterbore is required Whenever the inside Of the device is to be ground or otherwise finished so that the finishing tool may have a space in which to run out. Where such devices are of relatively large size, they may be formed readily from flat stock by means of dies, theA counterbored section being formed by an appropriately designed eX- panding die. Where the device is small,`how ever, as is the case of a trunnion bearing, there is not suicient room within the device for a sturdy and practical expanding die, and for this reason such small devices are generally produced from solid bars which are drilled out, and counterbored in a screw machine. The latter method is of course wasteful since the material drilled out is useless, and it is also a longer process.

The principal object of this invention is to provide a method of forming relatively small receptacles having a counterbore at or near the bottom thereof wherein the receptacle is made from fiat stock and Without the use of a screw machine.

A more specific object of this invention is to provide a method of making a trunnion bearing for a universal joint, the method employing only the ordinary solid punches and dies. Another specific object ofrthis invention is to provide a method ofrcontrolling the flow of metal in a blank such that although adjacent sections of the metal are acted upon by substantially the same force, one section will move while the other will remain stationary. f

These and other objects and features of this invention will become apparent from the following description when taken together with the accompanying drawing in which: l

Fig. 1 is a. fragmentary section taken through two portions of a die showing the die in its open position and about to perform the first operation upon a blank;

Fig. 2 shows the same die after the operation is completed;

Fig. 3 shows a second die performing the second operation upon the blank;

Fig. 4 is a fragmentary vsection through a third die showing the final step in the method; and

Fig. 5 is an enlarged fragmentary section through a trunnion bearing for a universal joint made by the method of this invention.

Referring first to 5 for a description of the receptacle or trunnion bearing, IB is a journal of across member IIAof a'universaljoint, said cross member being formed vwith a shoulder I2 against which is pressed a packing ring I3 which'is' held in place by a flanged washer I4. vSaid journal I5 operates withinV a trunnion bearing I5 which is heldinA oneA fork IB of a yoke member which in turn is secured'to one of the shafts (not shown) in the power train. Anti-friction rollers" I1 are inserted between trunnion bearing I5 and journals I0 to reduce the friction therebetween.

Trunnion bearing I5 isin the formof a cylinder having one end I8 closed and formed integrally therewith. The purpose of this construction is to prevent lubricant from being thrown `out from the bearing asA the jointis rotated. The end of journal IIJ bears against surface I9 of closedend I8 as doalso theends of rollers I` I`. Rollers I 'l roll on a surface 20 on'the inside of the cylindrical portieri of trunnion bearing I5. v Washer I4 4is pressed into a recess 2l in the open end'Y o f Ythe trunnion bearing.

It will be observed that surfaces I9 and V20 must be finished o if and surface '2 0 must be ground 'perfectly true. In orderthat thesenishing operations may be performed itis necessary that the inside corner of the bearing b e relieved to provide "a run-out for th'nnishing moi.' Forths reason surface 20 `is 'counterbred at 22 anda small groove is providedat 23 which brings into relief surface I9. Thus atool passing across surface 20 may run out'ihto the counterbore 22 and a tool moving acrosfsfsurfacelS may Vrun out into groove23.

It is obvious that the'formation of trunnion bearing I5 from around bar "by means 'ofdrilling and counterboring `Ltools may readily be accomplished but that if the bearing is'to be formedby means of dies alone the counterbore 22 and groove 23 present a problem. Surface 2 0 is" cylindrical and any die which is used toformcounterbore 22 must be able to Voo`r 1i",`raotinto the diameter of surface 20 if it is to bel withdrawn from thebearing. Such Aa die however, cannot be made sturdy enough where the bearing `is of the size normally used in present day pleasure automobiles. l'he method by which we have solved this problem will now be described.

The firstv step in our method is the formation of adisc-shapedblank fromat stock, the thickness and diameter of the blank'bein'g determined' aocording to the final dimensions of the trunnion bearing.

Next the disc-shaped blank is placed into a die as shown in Fig. 1. The die is comprised of a female member 24 having a, ared opening 25 which merges into a cylindrical section 26. A shoulder 21 is provided for properly centeringA the blank in the die. The male member 28 is provided with a rounded corner 29 and a flat end 39. Suitable knock-out pins 3| and 32 are provided in both portions of the die as is customary.

Fig. 2 shows the blank after it has been operated upon by the die shown in Fig. l. It will be observed that the blank is thicker at the bottom portion 33 and at the open endportion 34 and is thinner at the corner portion 35. This is done deliberately and no effort is made to make the corner portions 35 the same thickness as the remainder of the blank. It is important in this ilrst operation that the metal is not caused to work-harden to any appreciable extent and for this reason the corner region 35 is not formed against the female member of the di e.

The next operation is shown in Fig. 3. In this operation the blank is forced into a cylindrical opening 36 in the female portion 31 of the die by the male member 38 thereof. Opening 36 is of substantially the same diameter as the cylindrical portion 26 of the preceding die but it is tapered at 39 to a smaller diameterwhich corresponds to I the diameter vof the finished trunnion bearing. This taper permits groove 4|a to be formed in the blank by a simple reciprocating die, the Wider opening in the blank permitting the die to enter and leave the blank freely. Male member 38 has a corresponding taper 40 in the end thereof which forces a portion of the blank against the tapered portion'39 of-opening 36. Due to the thinning of the material at Vthe Vcorner in the preceding operation the pressureion the blank at the tapered region is very small and in fact a portion 4| of the blank remains untouched. This definitely prevents the material at the tapered region from Work-hardening and leaves it suiciently ductile to withstand a further change in form.

The bottom of the blank however is rpressed against a knock out pin 42 by the end of male member 38, said end having a flat surface 43 which is joined to the taper-40 by meansof a bead 44. Said bead 44 is pressed into the blank sothat the latter is coined and is work-hardened thereat. This work-hardening is limited to just that portion of the blank which is operated upon by the bead 44. Since this portion is work-hardened,I it will resist further change in shape and,

given an equal pressure `acting upon the workhardened portion and upon those portions immediately adjacent thereto, the latter will ow whereas the former will not. This controlled work-hardening ofthe material is an important feature of our method.

The last operation is shown in Fig. 4. In this operation the blank of Fig. 3 is forced into the opening 45 of thefemale portion 46 of a die, the opening being cylindrical and being of the same diameter as the nished trunnion bearing. Since this diameter is smaller than the diameter of the open end of the blank as it leaves the preceding die, the sides of the blank are necessarily forced radially inwardly against the male member 41 of the die. Said male member 41 has an outer diameter which fits snugly into the opening 45 and is also provided with a shoulder 48 and a section of reduced diameter 49, both of which are approximately of the iinished dimension. Reduced portion 49 is slightly smaller in diameter than the diameter of the finished bearing since allowance is made for a light grinding cut which must be taken in order to finish the bearing. The shoulder in male member 41 contributes considerable axial pressure which causes the sides of the blank to move axially to reduce the radius of the comer of the blank. Thus the sides are moved axially toward the bottom of the bearing and are also movedinwardly against the male member, and in so moving, there is a tendency to pile up the metal in the inner corner of the blank. Since this region was work-hardened in the preceding step, this piling up" tendency is resisted and as a result a counterbore is formed in the corner. 'Ihis of course is exactly what is desired and the blank may then be finished ofi on the inside with out any difliculty.

The foregoing method provides a closed receptacle with a counterbore therein which is very accurately made and which requireslittle machining. It canbe made with ordinary punch presses using standard multiple die apparatus so that the complete receptacle can be formed in a single press. Although the method has been described with reference to the making of a trunnion bearing for a universal joint it is understood that the method has a, wider application and that it can be used generally wherever a device similar to the trunnion bearing in size and configuration is to be made. It is understood therefore that the scope of the invention is not limited to the foregoing description but is to be determined by the appended claims.

We claim:

1. The method of forming a trunnion bearing for a universal joint, said bearing comprising a Vcylinder closed at one end and counterbored at the inside bottom regi-on to provide a run-out for a finishing tool, said method comprising forming into the shape of a cup an imperforate discshaped blank by means of a round nosed punch operating in a cylindrical die such that the bottom of the blank is not work-hardened at the bottom corner region thereof, Work hardening a circular region constituting a part of said bottom corner region and inside the blank, said circular region being of lesser diameter than 'the inside diameter of the open end of the blank, and then reducing the diameter and length of the blank against a cylindrical punch, the reduced inside diameter being smaller than the greatest diameter of the work-hardened region, whereby to form the counterbore in the blank, the workhardening of the circular region being accomplished by coining the bottom of the blank.

2. The method of forming a trunnion bearing for a universal joint, said bearing comprising a cylinder closed at one end and counterbored at the inside bottom region to provide a run-out for a nishing tool, said method comprising forming into the shape of a cup an imperforate discshaped blank by means of a round nosed punch operating in a cylindrical diesuch that the bottom of the blank is not work-hardened at the bottom corner region thereof, work hardening a circular region constituting a Dart of said bottom corner region and inside the blank, said circular region being of lesser diameter than the inside diameter of the open end of the blank, and then reducing the diameter and length of the blank against a cylindrical punch, the reduced inside diameter being Vsmaller than the greatest diameter of the work-hardened region, whereby to form the counterbore in the blank, the cupping resulting in a blank wherein the bottom and side walls are thicker than the corner region therebetween, and the reduction in the length of the blank being accomplished by upsetting the corner regions.

3. The method of forming a trunnion bearing for a universal joint, said bearing comprising a cylinder closed at one end and counterbored at the inside bottom region to provide a run-out for a finishing tool, said method comprising forming into the shape of a cup an imperforate discshaped blank by means of a round nosed punch operating in a cylindrical die such that the bottom of the blank is not work-hardened at the bottom corner region thereof, work hardening a circular region constituting a part of said bottom corner region and inside the blank, said circular region being of les'ser diameter than the inside diameter of the openend of the blank, and then reducing the diameter and length of the blank against a cylindrical punch, the reduced inside diameter being smaller than the greatest diameter of the work hardened region, whereby to form the' counterbore in the blank, the workhardening of the circular region being accomplished by coining a groove in the inside bottom of the blank to provide a run out for a nishing tool operating thereacross.

4.,The method of forming a trunnion bearing for a universal joint, said bearing comprising a cylinder closed at one end and counterbored at the inside bottom region to provide a run-out for a nishing tool, said method comprising forming into the shape of a cup an imperforate discshaped blank by means of a round nosed punch operating in a cylindrical die such that the bottom of the blank is not Work-hardened at the bottom corner region thereof, work hardening a circular region constituting a part of said bottom corner region and inside the blank, said circular region being of lesser diameter than the inside diameter of the open end of the blank, and then reducing the diameter and length of the blank against a cylindrical punch, the reduced inside diameter being smaller than the greatest diameter o1' the Work-hardened region, whereby to form the counterbore in the blank, and effecting simultaneously with the reduction in length the finishing of the end of the blank to form a shoulder therein.

DONALD H. CRAVENER, JR.

ROY C. INGERSOLL.

FRANS B. WENDEL. 

